1. Field of the Invention
The present invention concerns operations within telecommunication networks. Such networks contain many nodes. The function of each node is to relay and distribute information to other nodes or termination units. A node can be a single equipment, a complete system, or a small self-contained network. Each node is connected to other nodes using electrical, optical, radio, or satellite links.
2. Description of Related Art
If the link between two nodes is broken, or its performance is severely degraded, then the communication or traffic between the two nodes will fail. Therefore in telecommunications networks, it s necessary regularly to monitor the performance of all the links to identify any potential faults and in the event of a link failure to determine the location of the fault so that repair work can be started.
Normally testing of a link is performed when the traffic is off-line, i.e. when the traffic is removed from the link. Hence traffic is disrupted and communication between nodes is not possible during the testing periods. In addition, to test all the links on the network, a test facility must be provided for every node in the network. This latter requirement is very costly to the carriers, e.g. the companies who are providing the transmission service.